It has been known to obtain a coated article having a matted surface by electrocoating with an electrodepositable paint containing internally crosslinked micro resin particles (hereinafter referred to as "micro gel particles") prepared by polymerizing an ethylenically unsaturated monomer (see Japanese Patent Publication (unexamined) Nos. 93762/1983 and 49766/1981). The micro gel particles are advantageous not only in providing a matted surface, but also in affecting the coating properties and throwing power.
The micro gel particles, however, should be mixed with a resin which is water-soluble or water-dispersible and which has electric charges necessary for electrodeposition if it is applied to electrocoating, because they do not have suitable electric charges and are insoluble in an aqueous medium. On the other hand, the micro gel particles deteriorate storage stability and workability of the electrocoating and it therefore is difficult to formulate into a paint in a large amount.
Japanese Patent Publication (unexamined) No. 31199/1986 discloses an electrocoating composition for providing a matted surface prepared by neutralizing a heat reaction product of an alpha, beta-ethylenically unsaturated polycarboxylic acid resin with an alkoxylated methylolmelamine. In this procedure, since the resin mixture is heated before uniformly emulsifying, it happens, when heating is carried out too long, the molecular weight comes too high and therefore it becomes difficult to dissolve the resin in water.